The advancement of turbomachinery performance is related to both the overall pressure ratio of the machine and the turbine inlet temperature that can be reliably sustained during operation. Increases in efficiency pressure ratio or inlet temperature typically produce a higher temperature operating environment for the turbine flow-path hardware. The working fluid in the flow path is typically several hundreds of degrees Fahrenheit higher than the melting point of the alloys that typically make up the turbine flow-path hardware. To counter the high temperature working fluid, dedicated cooling air may be extracted from the compressor and routed to cool the gas path components in the turbine, incurring significant cycle penalties.
For extremely high temperature applications, film cooling and backside convection may be utilized. Film cooling uses cooling air delivered to an internal volume of a component to emit a cooling flow over the external surface of the component. The cooling flow may form a film over the external surface of the component that reduces the local external surface temperatures downstream.